Method of treatment of cocoa butter-containing molten chocolate mass

ABSTRACT

A method of treatment of substances containing cocoa butter, particularly chocolates, which is suitable for coating machines, wherein the material containing cocoa butter is first heated slightly above the highest melting point of cocoa butter, then subjected to a two stage cooling step whereby the material in first cooled to a range approximately 30* to 31* C. by a cooling medium having a temperature only slightly lower than this range and secondly cooling the mass to 28* to 29* C. by a cooling medium having a temperature only slightly lower than this range, and then heating the material to 33* to 34* C. and subjecting to further processing (i.e. coating). The material after this treatment is in a thermostable condition, has a substantially constant viscosity and may be stored indefinitely under stirring and when maintaining the temperature of the temperature of the material.

United States Patent Kreuter 1 Feb.l,l972

[54] METHOD OF TREATMENT OF COCOA BUTTER-CONTAINING MOLTEN CHOCOLATEMASS Walter Kreuter, Essener Str. 104, Hamburg 62, Germany 22 Filed:Sept. 4, 1969 211 Appl.No.: 855,318

[72] Inventor:

Williams, C. Trevor Chocolate and Confectionery Leonard Hill Books,Limited, London (1956) pp. 132- 134 Primary Examiner-A. Louis MonacellAssistant Examiner-William A. Simons Attorney-Beaman & Beaman [57]ABSTRACT A method of treatment of substances containing cocoa butter,particularly chocolates, which is suitable for coating machines, whereinthe material containing cocoa butter is first heated slightly above thehighest melting point of cocoa butter, then subjected to a two stagecooling step whereby the material in first cooled to a rangeapproximately 30 to 31 C. by a cooling medium having a temperature onlyslightly lower than this range and secondly cooling the mass to 28 to 29C. by a cooling medium having a temperature only slightly lower thanthis range, and then heating the material to 33 to 34 C. and subjectingto further processing (i.e. coating). The material after this treatmentis in a thermostable condition, has a substantially constant viscosityand may be stored indefinitely under stirring and when maintaining thetemperature of the temperature of the material.

1 1 Claims, 2 Drawing Figures PATENTEU FEB I E72 SHEET 1 BF 2 IN VENTORPATENIEB FEB H972 3.638.553

SH 2 HF FIG.1b

IN VENTOR METHOD OF TREATMENT OF COCOA BUTTER- CONTAINING MOLTENCHOCOLATE MASS In the manufacture of chocolate bars and chocolate coatedarticles, such as cream chocolates, a correct treatment of the chocolatesubstances supplied in fluid condition is of decisive importance for theappearance and the keeping qualities of the product. The treatmentcomprises cooling and heating procedures which constitute essentialsteps of the method of treatment and are, as a whole, also calledtempering or preliminary crystallization. During this treatment, cocoabutter crystals are developed in the substance and since the cocoabutter is polymorphous, it is assumed that the empirical dependence ofthe resulting'processing quality on the type of treatment may beattributed to the formation of crystal nuclei of different modificationsin accordance to the different temperatures to which the substance issubjected during the treatment. However, only nuclei of the most stablemodification having the highest melting point are desired in thesubstance ready for processing. If the treatment is unsuitable, thefinished chocolate which has been processed and solidified has only adull gloss and an inhomogeneous structure which is characterized by greytones or brighter spots. Sooner or later, particularly with high storagetemperatures, the so-called fat bloom" will develop which severelyimpairs the appearance of the manufactured goods. With correct treatmentof the substance, however, chocolate products are obtained which havesmooth, uniform and relatively dark colored surfaces having an intensivegloss. These products have a relatively high temperature stability andstorage quality and show little tendency to form fat bloom.

In prior art treatment methods, the substance which has been heatedbeyond its highest melting temperature is cooled down under stirring,mixing and scraping to the processing temperature of about 31 to 30 C.During this cooling procedure, the substance is brought into heatexchange relationship with a cooling medium which has a relatively lowtemperature such as water of about C. The result of the stirring andscraping at the cold walls of the heat exchanger through which thecooling medium is circulating is that the substance which has beencooled down in the vicinity of the heat exchanger to a comparatively lowtemperature is again mixed with the rest of the substance which is stillat a higher temperature and thus the cooled substance is again heated upto the desired temperature.

The viscosity of a substance which has been treated according to thedescribed conventional method remains, but varies even when keeping thetemperature constant; in fact, the viscosity of the substance increasesrelatively quickly so that the treated substance is usable for a limitedperiod of time only. This represents a considerable disadvantageparticularly in the production of chocolate coated articles, since thecoating of articles is normally carried out by pouring the chocolatesubstance inside a coating box over the articles to be coated anddecanting the excess chocolate again from the coating box. Since theviscosity of the chocolate substance which has been tempered in theconventional manner does not remain constant, the excess quantitydischarged from the coating box may be reused only during a limitedperiod of time, without having recourse to retemperi ng. The viscosityof the substance increases steadily until finally the produced coatingswill become too thick and uneven so that the substance must beretempered, i.e., heated above its highest melting point and thentreated in the above-described manner, before it can be reused. In thepractical operation, it is attempted to delay this gradual thickening ofthe tempered chocolate by certain methods, for example by addinguntempered chocolate substance to the already thicker substance. Throughthis type of remedial measure the increase of the viscosity up to avalue unusable for processing can, however, only be delayedinsignificantly, and furthermore, the success of this type of measuredepends to a very large degree upon the skill and the experience of theoperators. Even when having recourse to this type of measure, the majorproportion of the excess substance discharged from a coating machinemust eventually be tempered anew, since, with conventional coatingmachines a relatively small fraction of the total chocolate quantitysupplied to the coating box is used up and the larger portion representsa leftover excess quantity, the viscosity of which does not remainconstant. This prior method is very uneconomical since the necessaryreheating of a larger portion of the chocolate substance results in ahigh energy consumption and furthermore correspondingly large apparatusfor the reheating and cooling (tempering or preliminary crystallization)is required.

The prior art treatment or tempering plants may be designed separatelyin the form of a tempering machine or may be incorporated directly intoa coating machine. A coating machine having built-in tempering meansgenerally is operated according to the method of cyclic tempering oraccording to the method of multicircuit tempering. ln the method ofcyclic tempering, the chocolate substance is continuously retempered andremelted, in order to prevent the substance from reaching the conditionof so-called overtempering which is characterized by the above-describedsteep increase of the viscosity of the substance. The viscosity increaseis accompanied by self-heating of the chocolate substance, as a resultof the heat of crystallization released. The method of cyclic temperingthus leads to a chocolate substance in which there is no thermostaticequilibrium between solid and fluid phases. An overtempered chocolatesubstance is unsuitable for processing since the formation of fat bloomis instantly initiated. Especially the large-sized cocoa-butter crystalsare responsible for this formation of bloom. Fissures appear between thelarge and the small crystals as a result of the volume contraction.Light isscattered by these fissures and small white fat bloom stars areobserved on the surface of the chocolate. In order to avoid thesedefects, the substance must be continuously retempered. For example, fora coating unit having an article conveyor belt of 800 mm. width 2,000kg. of chocolate substance per hour must be tempered and melted,although the actual consumption normally amounts to only between 200 to250 kg. per hour. From these figures it is seen that the method ofcyclic tempering is highly uneconomical.

With the method of multicircuit-tempering, in particular with the methodof two-circuit-tempering, a molten chocolate substance is cooled byscraping in the first section of a tempering apparatus, and in thesecond section of the apparatus it is mixed with a tempered chocolatesubstance and somewhat heated up. After leaving the tempering apparatus,the chocolate substance is ready for processing. The mixing of thecooled chocolate with the tempered warm chocolate substance may beregarded as an inoculation of the cooled substance with more stablecocoa butter crystallization nuclei. As a result of the relatively highviscosity and the poor miscibility of the chocolate substance, thisinoculation is not homogeneous so that local differences occur withregard to the number of more stable cocoa butter crystallization nucleiper unit volume. Furthermore, inhomogeneities in the temperaturedistribution can hardly be completely avoided when mixing two chocolatesubstances having different temperatures. It follows therefore that asubstance which has been treated in this way does not release its heatcontent evenly, and in particular its heat of crystallization, afterprocessing when cooling the substance in a cooling duct. This can leadto partial melting of the stable cocoa butter crystals, thereby formingsmall pockets of fluid instable cocoa butter. These pockets laterefflorescence in forming fat bloom. In the two-circuit method, thechocolate substance must likewise always be reheated beyond its highestmelting point (and thereby melted) and be retempered so that thesubstance does not reach the stage of overtempering. This means thathere too, no thermostatic equilibrium exists between the formed morestable cocoa butter crystallization nuclei and the instable cocoa buttermolecules in the fluid phase. The overtempering is therefore notprevented even with a two-circuit tempering method.

Although the two-circuit method is somewhat more economical because onlyhalf the substance must be retempered, the two described prior arttempering methods are essentially similar to each other with respect toprocessing technique and are subjected to the same disadvantages.

ln order to avoid the above-mentioned disadvantages, it has already beenproposed to preliminarily crystallize a molten chocolate substance bytwice cooling and reheating. In this way, the substance is at firstgently cooled down to a temperature of about 29 C. and then kept at thistemperature until the viscosity reaches a maximum. Then the substance isheated up to about 33 C. and kept at this temperature until theviscosity remains constant. Then the substance is again gently cooleddown without undercooling, to 29 C. and then kept at this temperatureuntil the viscosity has again reached a maximum. Finally the substanceis again heated to 33 C. A substance treated in this manner should havea constant viscosity over longer periods (it would naturally be aprerequisite in any case that the temperature of the treated substancewhich is continuously stirred be kept constant).

The last-described so-called cyclotherrnal preliminary crystallizationhas not yet been practically employed in a tempering machine. Thereheating and recooling is rather cumbersome and requires a fairlycomplicated apparatus which must be operated with care, and which haswith regard to energy consumption the additional disadvantage thatheating is necessary twice. If the method is to be employed forcontinuous operation, at least four heat exchangers are required.

it is an object of the present invention to provide a method oftreatment of substances containing cocoa butter, in particularchocolates by which a processable substance may be obtained in a simplemanner wherein the substance does not need to be heated twice and thesubstance thus treated has a substantially constant viscosity overrelatively long periods and has all the properties of a well-temperedsubstance.

it is a further object of the present invention to provide an apparatusfor carrying out the above-described method.

For achieving the objects stated above, there is proposed, according tothe present invention, a method of treatment of substances prepared forprocessing and containing cocoa butter, particularly chocolates,according to which a substance which has been heated to a firsttemperature above the highest melting point of the substance is cooleddown to a predetermined second temperature, preferably within a rangefrom about 28 to about 29 C., then the substance is again heated upwithout overheating to a predetermined third temperature, preferablywithin a range from about 33 to about 34 C. whereby the thirdtemperature is lower than the first temperature and the method of theinvention is characterized in that the cooling from the firsttemperature to the second temperature is effected in two stages wherebyan intermediate temperature at the end of the first stage is preferablywithin a range from about 30 to 31 C. and whereby in both stages thesubstance is cooled by a cooling medium, the temperature of which ineach of these two stages is only slightly lower than the finaltemperature of the substance in each of these respective stages.

It has been shown that a substance treated according to the method ofthe invention has a viscosity which remains constant over long periodsof time at the third or the final temperature, and that such asubstance, after processing, results in products which have all desiredproperties of a high quality chocolate surface. The method of theinvention is more simple and more economical than the known methods inwhich cooling and reheating is effected twice, since the method of theinvention may be carried out at the expense of less time and energy;these simplifications lead to a considerable saving of costsparticularly if automatic control devices are employed. Since the methodof the invention is basically similar to conventional simple methods oftreatment or tempering having only a single cooling step and a singleheating step, the method of the invention may be carried out in manycases by employing existing conventional treatment apparatus.

It may be practical to keep the substance for a predetermined time, t'orexample for 5 minutes, at the intermediate temperature. According to afurther refinement of the invention the treated substance may be pouredinto a storage reservoir and kept therein at the third temperature,i.e., stored ready for processing. This allows batch operation which isad vantageous for several reasons. For example, it is possible to treatseveral small quantities of substance subsequently and to fill thesequantities into the storage reservoir when using a relatively smalltreatment and tempering apparatus in the form of a conventional dishtempering machine. The substance which is ready for processing may thenbe taken out of the storage container in desired quantities which mayalso vary. It is of course likewise possible to feed several storagecontainers from a single tempering machine. The method of the inventionis particularly advantageous in those cases in which the substance isprocessed in excess after a single cooling and reheating at about thethird temperature. The excess substance resulting during processing maythen be kept at the third temperature and reused without cooling thesubstance down to the first temperature. in this case the viscosity ofthe substance does not increase with time to such a value necessitatingrenewed treatment (tempering) of the whole substance after heating upthe substance beyond its highest melting point. The consumption, i.e.,the quantity of substance used up during processing may be compensatedfor by the addition of supplementary quantities of treated substancewhich are at the third temperature. If a storage reservoir of theabove-described type is employed, the supplementary quantity may betaken from this storage reservoir so that this storage reservoir servesas a buffer between the processing apparatus and the treatment ortempering apparatus. in this way it is possible to shield the treatmentapparatus from strong fluctuations in the feed of the supplementaryquantity such as may be encountered with the supplementary quantitysupplied. lt goes without saying that the supplementary quantity mayalso be taken directly from the treatment apparatus; in this case thetreatment apparatus or the processing apparatus figures as the storagereservoir. It is likewise possible to employ a continuously cyclingtreatment apparatus which feeds to a storage reservoir or is adapted tosupply the supplementary quantity directly. in each of these cases theadvantage is that renewed treatment of the excess substance resultingfrom processing is unnecessary.

The above-described method of operation in which the substance istreated in excess is particularly suitable for coating machines. Forcarrying out this method there is proposed, according to the presentinvention, an apparatus comprising a circuit including a processing unithaving an inlet for the supply of substance and an outlet for thedischarge of excess substance, a circulation container disposed in linewith at least one conveyor apparatus between the inlet and the outlet ofthe processing unit whereby the apparatus additionally comprises asupplementary supply line connected to this circuit and adapted todischarge a substance into this circuit, and a tempering apparatus forthe treatment of the substance through the cooling and heating procedurewherein this apparatus is characterized in that the tempering apparatusis disposed completely externally to the circuit and is connected tothis circuit only through the supplementary supply line. As has beenmentioned above already, it is practical to provide a storage reservoircomprising means for maintaining the temperature between the temperingapparatus and the supplementary supply line. A fluid flow control meanssuch as a valve or a pump which is controlled by the level in thecirculation container may be provided in a manner known per se for thecontrol of the supplementary quantity delivered. The tempering meansneeds only to be dimensioned according to the consumption of substancein the processing unit. Normally, the tempering apparatus will have acertain excess capacity but this does not alter the fact that theteaching of the present invention allows to use considerably smallertempering apparatus for coating machines, in comparison to conventionaltreatment or tempering methods.

In the following, the invention will be described by means of variousexamples and in connection with the attached drawmg.

As the following first example shows, the method of the invention may bepracticed also in using conventional tempering apparatus. In aconventional dish tempering machine of the type Kreuter TM 100 having awater-heated jacket, 25 kg. of chocolate supplied at an initialtemperature of 40 C. (first temperature) were at first cooled downduring 30 minutes at a cooling water temperature of 30 C. to anintermediate temperature of 29.9 C. This intermediate temperature wasmaintained for minutes. Then the cooling water temperature was reducedto 26 C., and after a further 30 minutes the temperature of thesubstance was 27.8 C. (second temperature). Then the water temperaturewas increased to 33.5 C., and after further 30 minutes the temperatureof the substance likewise was about 335 C. This temperature wasmaintained constant by automatic control and it was observed that theviscosity of the substanceremained unchanged even after a long time. Thetest was abandoned after 60 hours.

It is also feasible to further subdivide these two cooling steps,although the two-stage cooling will be preferred because it representsthe simplest processing technique. Merely in order to demonstrate that amultistage cooling is feasible the following test was carried out: 25kg. of chocolate substance having an initial temperature of 37 C. werefilled into the already mentioned dish tempering machine of the typeKreuter TM 100 and cooled initially for 45 minutes at a watertemperature of 30 C. The resulting intermediate temperature of thesubstance was then likewise 30 C. Then the cooling water temperature wasreduced to 28 C., and after 10 minutes the temperature of the substancewas 29 C. Then the cooling water temperature was further reduced to 26C. After the substance had again reached (as in the previous example) atemperature of 27.8 C.', the water temperature was increased to 33.5 C.,and after 30 minutes the temperature of the substance was again about 33to 33.5 C. The substance treated in this manner likewise did not showany noticeable decrease of its viscosity after 60 hours.

The accompanying FIGS. 1a and lb drawings schematically illustrate anapparatus for the coating of articles with chocolate, in which themethod of the invention is applied.

The apparatus illustrated in the Figures comprises a processing unit Iin the form of a conventional coating box for the coating of articleswith chocolate. The coating box includes an inlet 2 for the feeding ofsubstance and an outlet 3 for the discharge of excess substance. Theexcess substance is discharged from the outlet 3 into a circulationcontainer 4 having a drain 5 connected via a pipe 6 to a conveyor devicesuch as a pump 7 which conveys the substance to the inlet 2 of thecoating box 1. The circuit consisting of coating box I, circulationcontainer 4 and conveyor device 7 is connected to a supplementary supplyline 8 which in the illustrated apparatus opens into the circulationcontainer 4 and is adapted to supply a supplementary quantity of treatedsubstance which compensates the consumption in the coating box I. Theabove described parts may be heated in order to keep the substancecirculating in the processing circuit at a predetermined temperature. Asshown in FIG516, the connection pipe 6, the supplementary supply line 8and the circulation container 4 are provided with heating jackets 9, l0,11, respectively, which are supplied with a heating medium, normallywater, by a thermostat controlled heating device 12. As seen in FIG. lb,the heating device 12 and its components are only schematicallyillustrated; the reference numeral 13 designates electric heater coilsand the reference numerals l4 and 15 designate valves for cold waterinflow and cold water discharge. The heating medium which has beenheated by the heating device 12 to a predetermined temperature in theconventional manner is circulated by means of a pump 16 through a feedline 17, the heating jacket 9 of the connecting pipe 6, through afurther connecting pipe 18, the heating jacket 10 of the supplementarysupply line 8, through a further connecting pipe 19, the heating jacket11 of the circulation container 4 and through a return line 20. Thecontrol devices for the thermostatic control of the heating medium arenot shown.

A substance 21 contained in the circulation container 4 is maintained ata predetermined temperature by the heating 5 jacket ll; the temperatureof the heating medium circulating in the heating jacket 11 may of coursealso be controlled by a temperature sensor (not shown) which responds tothe temperature of the substance 21. The substance 21 is filled into thecirculation container 4 in treated (tempered) condition, and the heatingof the circulation container is controlled in such a manner that thesubstance contained therein is maintained substantially at the finaltemperature of the treatment or tempering process. Since the,viscosityof the substance treated according to the method of the presentinvention does not change even over prolonged periods when maintainingthe substance at its final temperature, the substance in the circulationcontainer 4 which is circulated through the coating box 1 remains in thetreated (tempered) condition and may be continuously reused without anydanger of a thickening of the substance.

A level sensor 22 is provided inside the circulation container 4 and isadapted to control the discharge of treated substance from thesupplementary supply line 8 into the circulation container 4 in aconventional manner. FIG. lb illustrates schematically a pilot line 23leading to a pump 24 which is arranged at the inlet of the supplementarysupply line 8. If the level of the substance in the circulationcontainer 4 drops below a predetermined height the pump 24 is put intooperation and supplies freshly treated substance into the circulationcontainer until a predetermined level of the substance has been reachedat which the pump 24 will be switched off by a signal from the levelsensor 22.

In the apparatus shown in the FIGS. the supplementary supply line 8 isfed from a storage reservoir 25 in which treated substance 21 is keptunder continuous stirring at a constant temperature. As schematicallyillustrated in the Figure, the storage reservoir 25 comprises anagitator 26 connected to a drive motor 27. The outlet 28 of the storagereservoir 25 is connected to the inlet of the pump 24. The storagereservoir 25 may be filled with treated substance from an inlet line 29.

The storage reservoir 25 and its components may likewise be heated. TheFIGS. illustrate a heating jacket 30 for the storage reservoir 25 and aheating jacket 31 for the inlet line 29. A controlled heating andconveying device 32 circulates a heating medium which preferablyconsists of water through the heating jackets 30 and 31 and a returnline 33. The temperature of this heating cycle may be controlled by anymeans known to the one skilled in the art, for example by means of atemperature sensor (not shown) responsive to the temperature of theheating medium and/or the temperature of the substance in the reservoir25.

IN the apparatus illustrated, the feeding of the treated substance intothe storage reservoir is effected by means of a pump 34 connnected to anoutlet 35 of a tempering apparatus 36 according to the invention whichserves to treat a substance by cooling and heating.

The tempering apparatus shown in FIG. la is adapted to batch productionin a manner similar to a conventional dish tempering machine. Thetempering apparatus comprises a vessel 37 with a built-in agitator 38powered by an electric motor 39. Outlet pipes are connected to the lowerend of the vessel 37; two outlet pipes 40 and 41 are indicated in theFIG. In. These outlet pipes lead to heat exchangers 42 and 43,respective, which may be conventional heat exchangers such as narrow-gapheat exchangers.

From the opposite ends of the heat exchangers 42, 43 the substancerecirculates into the vessel 37 of the tempering apparatus. In order topass the substance through the heat exchangers, these heat exchangersare provided with conveyin g devices (not shown) or the heat exchangersthemselves are arranged in the manner of a conveying device. Forexample, the heat exchangers may be provided with screw conveyors in aknown manner. Conveying means and drive means therefore which are knownper se are not shown in the drawing. A supply line 46 for untreated(untempered) substance opens into the vessel 37.

The substance contained in the heat exchangers 42, 43 and in the vessel37 may be cooled or heated in the manner desired by the method of theinvention by means of a tempering medium which preferably consists ofwater and is adapted to be controllably heated or cooled. For thispurpose, the vessel 37 is provided with a heating jacket 47 throughwhich the temper-ing medium circulates. The tempering medium alsocirculates through the heat exchangers 42 and 43; as shown in the Figurethese heat exchangers are provided with heating jackets 48, 49respectively. The tempering medium may also be circulated in a mannerdifferent from the one shown. Preferably the supply line 46 foruntempered substance is provided with a heating jacket 50 through whichhot water supplied from a source of hot water (not represented)circulates. The tempering medium, preferably water, is cooled and heatedin the desired manner in a combined heating and cooling device Sl. Thecombined heating and cooling device 51 is only illustrated schematicallyin FIG. 1a in which heater coils 52, a cooling water supply line 53, acooling water discharge line 54 and control valves 55 in the coolingwater supply line are shown.

The tempering medium which is preferably water is supplied from thecombined heating and cooling device 51 by means of a pump 56 through apipe 57 into the tempering machine proper; in the apparatus illustratedthe components of the tempering apparatus 36 through which the temperingmedium circulates are connected in series, the tempering medium arrivingin pipe 57 passes through the heating jacket 48 of the first heatexchanger 42, then through a connecting pipe 58, the heatingjacket 47 ofthe vessel 37, a second connecting pipe 59, the heating jacket 49 of theheat exchanger 43 and through a return line 60.

The heating and cooling in the combined heating and cooling device 51 iscontrolled by a program control unit in response to the temperatures ofthe substance and the tempering medium. The temperature of the substancecontained in the tempering apparatus 36 is indicated by a temperaturesensor 61, and the temperature of the tempering medium is measured by atemperature sensor 62 in the combined heating and cooling device 51. Thetwo temperature sensors 61 and 62 may be connected as shown in the FIG.la to indicating controllers 63 and, respectively. The program controldevice is indicated schematically at 65.

The apparatus shown in FIG. la is adapted to batch production. Thevessel 37 of the tempering apparatus 36 may be provided with a levelsensor (not shown) which initiates tempering as soon as the vessel 37has been filled to a predetermined level with substance discharged fromthe supply line 46. Then a valve (not shown) in the supply line 46 isclosed (whereby the pump 34 provided at the drain of the vessel 37 islikewise closed). A predetermined treatment program may be preselectedby means of the program control device 65. The precise data of such aprogram depend somewhat on the kind of cocoa butter containing substancesuch as chocolate to be treated.

As soon as the program has been started manually or automatically apredetermined desired temperature of the tempering medium will beregulated by means of the temperature sensor 62 which responds to thetemperature of the tempering medium. in the method of the invention thesubstance which has been filled into the vessel 37, must at first begently cooled down to the intermediate temperature in the range fromabout 30 to about 31C. by means of a tempering medium the temperature ofwhich is only slightlylower than this intermediate temperature.Accordingly, in this first cooling stage the desired control temperatureof the controller 64 responsive to the temperature sensor 62 may beadjusted to about 29.5 C. Then the heating and cooling device 51 will becontrolled automatically by switching on the heater coils 52 or openingthe control valves 55 for the cooling water so as to circulate thetempering medium at a temperature of about 295C. through the heatexchangers 42 and 43 and the heating jacket 47 of the vessel 37. As soonas the substance which is continuously stirred by means of the agitator38, 39, reaches the desired intermediate temperature at the end of thefirst stage which will be controlled by the sensor 61 and the controller63 connected to this sensor the first cooling stage is terminated andthe second cooling stage may be initiated. Therefore, as soon as theprogram control device 65 receives a signal from the sensor 61responsive to the temperature of the substance indicating that theintermediate temperature has been reached the program control device 65switches over to the second cooling stage in which the substance iscooled down to a predetermined second temperature preferably in therange from about 28 to about 29 C. The desired value of the temperaturecontrol of the tempering medium will be automatically reduced to a valuesomewhat below the desired temperature such as, for example, 275 C. sothat the temperature of the tempering medium may be reduced to thisvalue and kept constant at this value. After a certain time has expiredthe substance in container 37 has reached the desired second temperature of for example 28.5 C. and the controller 63 responsive to thesensor 61 switches the program control device further to the heatingstage in which the substance is to be heated without overheating up to apredetermined third-temperature which is preferably in the range from 33to about. 34 C. in this stage, the desired value of temperature controlof the tempering medium is adjusted correspondingly, for example to345C. and the tempering medium circulating through the heat exchangers42 and 43 and the heatingjacket 47 of the vessel 37 is adjusted to thistemperature. After a certain time the substance contained in the vessel37 will have reached the desired third temperature of, for example, 33.5C. This condition will again be indicated by the temperature sensor 61and from this point onwards this temperature sensor 61 will take overthe further temperature control of the tempering medium so that thetemperature of the substance will be substantially maintained at thethird temperature. The design and the construction of a regulatingdevice or a program control unit for carrying out the above describedsteps is not difficult for one skilled in the art; therefore it appearsunnecessary to described such a control device in detail. Such a type ofcontrol device naturally permits automatic control of other processessuch as maintaining the substance for a predetermined time interval atan intermediate temperature or automatically switching on and switchingoff the pump 34 at the end of a complete treatment process andautomatically discharging the contents of the vessel 37 into the storagereservoir 25. The renewed filling of the vessel 37 with untemperedsubstance from the supply line 46 may also be effected automatically bythe program control device 65.

With the above described apparatus, the temperatures of the temperingmedium such as water are maintained substantially constant in everystage of the inventive method. These temperatures may be selected veryclose to the desired final temperature of the substance in each stage sothat the cooling or the heating, respectively, in each stage may beeffected very gently. The difference between the desired finaltemperature of the substance in a stage and the temperature of thetempering medium will of course be selected not too small in order tokeep the time required for these treatment steps within reasonablelimits.

The method of the invention may of course be also employed forcontinuous operation, for example by leading a stream of substance to betreated through three heat exchangers connected in series of which thefirst two heat exchangers effect the cooling in two stages and the thirdheat exchanger effects the heating of the substance to the third orfinal temperature.

The progress achieved by the present invention may be illustrated with areference to some numerical data. When using a modern coating machinehaving a conveyor belt width of 800 mm. about 2,000 kg. of chocolate perhour are circulated through the coating box 1. Of this quantity ofchocolate only about 150 kg. per hour are actually used up and about1,850 kg. of chocolate per hour return through the outlets 3 to thecirculation container 4. Whereas with conventional prior art coatingmachines the total circulating chocolate quantity (in the presentexample about 2,000 kg. per hour) or at least a substantial portion ofthis quantity had to be treated by the method of cyclic tempering or bythe method of multicircuittempering, the method of the present inventionrequires to replace only the actual consumption (in the present examplethe 150 kg. per hour) by a supply of treated substance. Although, inprinciple, it was hitherto feasible to operate the coating machine for acertain time without partially or wholly retreating the circulatingchocolate mass, deficiencies were incurred in as much as the gradualthickening of the substance could not be predicted accurately and couldhardly be influenced. In many cases and for the sake of a prolongedcontinuous operation the coating machine was operated until thesubstance had thickened to a considerable degree; this of course resultsin a higher consumption of substance and thereby in higher costs, quiteaside from the nonuniformity of the manufactured articles. In any case,all of the substance contained in the coating machine had to beretempered after a certain operation time and, additionally, in manycases it was even necessary to heat up the entire coating machine, inorder to be able to remove the stiffly thickened substance from themachine.

A substance which has been treated according to the method of theinvention is in a thermostable condition and may be stored indefinitelyunder stirring and when maintaining the temperature of the substance.

Further modifications are possible without departing from the scope ofthis invention.

lclaim:

l. A method of treatment of cocoa butter containing molten chocolatemass for subsequent processing comprising the steps of heating the massto a first temperature slightly above the highest melting point of thecocoa butter cooling the mass in two subsequent stages to apredetermined second temperature while being agitated comprising coolingthe mass at the end of the first stage of a range approximately 30 to 31C. by a cooling medium having a temperature only slightly lower thanthis range, and then cooling the mass in a second stage to said secondtemperature of approximately 28 to 29 C. by a cooling medium having atemperature only slightly lower than said last-mentioned range, and thenheating the mass to a predetermined third temperature of approximately33 to 34 C., said third temperature being lower than said firsttemperature.

2. A method as claimed in claim 1, characterized in that said coolingmedium temperatures in said two stages are approximately 30 and 26 C.,respectively.

3. A method as claimed in claim 1, characterized by the further step ofdischarging the reheated mass into a storage reservoir keeping it storedtherein at said third temperature in tempered condition ready forprocessing.

4. A method as claimed in claim 1, characterized in that the temperatureof said cooling medium in said first stage is higher than the finaltemperature of said mass in said second stage.

5. A method as claimed in claim 1 characterized in that said mass iskept at said temperature at the end of said first stage for apredetermined interval.

6. A method as claimed in claim 5, characterized in that said intervallasts at least 5 minutes.

7. A method as claimed in claim 1, wherein said processing is performedwith an excess quantity of tempered mass at about said thirdtemperature, characterized in that the residual quantity of said massobtained after said processing is kept at said third temperature andrecycled for continued processing without intermediate cooling down tosaid second temperature. I

8. A method as claimed in claim 7, characterized by supplying saidtempered mass to said processing at a rate corresponding to the quantityused as a result of said processing, said tempered mass being suppliedat said third temperature.

9. A method as claimed in claim 8, characterized in that said temperedmass is supplied from a storage reservoir wherein said mass isaccumulated after said tempering and kept stored therein at said thirdtemperature in a tempered condition ready for said processing.

10. A method as claimed in claim 1, characterized in that at least oneof said cooling stages is subdivided into further stages.

11. A method as claimed in claim 10, characterized in that thetemperature of said cooling medium in a stage is higher than the finaltemperature of said mass in a subsequent stage.

2. A method as claimed in claim 1, characterized in that said coolingmedium temperatures in said two stages are approximately 30* and 26* C.,respectively.
 3. A method as claimed in claim 1, characterized by thefurther step of discharging the reheated mass into a storage reservoirkeeping it stored therein at said third temperature in temperedcondition ready for processing.
 4. A method as claimed in claim 1,characterized in that the temperature of said cooling medium in saidfirst stage is higher than the final temperature of said mass in saidsecond stage.
 5. A method as claimed in claim 1 characterized in thatsaid mass is kept at said temperature at the end of said first stage fora predetermined interval.
 6. A method as claimed in claiM 5,characterized in that said interval lasts at least 5 minutes.
 7. Amethod as claimed in claim 1, wherein said processing is performed withan excess quantity of tempered mass at about said third temperature,characterized in that the residual quantity of said mass obtained aftersaid processing is kept at said third temperature and recycled forcontinued processing without intermediate cooling down to said secondtemperature.
 8. A method as claimed in claim 7, characterized bysupplying said tempered mass to said processing at a rate correspondingto the quantity used as a result of said processing, said tempered massbeing supplied at said third temperature.
 9. A method as claimed inclaim 8, characterized in that said tempered mass is supplied from astorage reservoir wherein said mass is accumulated after said temperingand kept stored therein at said third temperature in a temperedcondition ready for said processing.
 10. A method as claimed in claim 1,characterized in that at least one of said cooling stages is subdividedinto further stages.
 11. A method as claimed in claim 10, characterizedin that the temperature of said cooling medium in a stage is higher thanthe final temperature of said mass in a subsequent stage.